Spatially resolved filament wavefront dynamics.

Spatially resolved wavefront measurements are presented during nonlinear self-collapse and provide the first detailed characterization of wavefront evolution during filament formation. The wavefront dynamics of key nonlinear processes including Kerr self-focusing, ionization and plasma defocusing, and dynamic spatial replenishment are identified and resolved in both the filament core and reservoir regions. These results are analyzed and interpreted with respect to numerical simulations and provide insight into fundamental aspects of filamentation.

Direct wavefront measurements of filaments in the assisted-collapse regime.

Wavefront measurements are used to characterize the process of filament formation in air under assisted-collapse conditions. Direct wavefront evolution within the filament, measured for the first time, is used to characterize the role of energy reservoir in filament formation. This information provides new insights into the filament process and phase sensitive applications such as engineered plasma waveguides.

Synthesizing broadband propagation-invariant space-time wave packets using transmissive phase plates.

Space-time wave packets are a class of pulsed optical beams that are diffraction-free and dispersion-free in free space by virtue of introducing a tight correlation between the spatial and temporal degrees of freedom of the field. Such wave packets have been recently synthesized in a novel configuration that makes use of a spatial light modulator to realize the required spatio-temporal correlations. This arrangement combines pulse-modulation and beam-shaping to assign one spatial frequency to each wavelength according to a prescribed correlation function.

Single-shot, volumetrically illuminated, three-dimensional, tomographic laser-induced-fluorescence imaging in a gaseous free jet.

Single-shot, tomographic imaging of the three-dimensional concentration field is demonstrated in a turbulent gaseous free jet in co-flow using volumetrically illuminated laser-induced fluorescence. The fourth-harmonic output of an Nd:YAG laser at 266 nm is formed into a collimated 15 × 20 mm beam to excite the ground singlet state of acetone seeded into the central jet. Subsequent fluorescence is collected along eight lines of sight for tomographic reconstruction using a combination of stereoscopes optically coupled to four two-stage intensified CMOS cameras.